Conventional fluorescent lamps generally consist of an elongated glass tube surrounding two electrodes, a phosphor that absorbs radiation at given wavelengths and reradiates energy at longer visible light wavelengths, and an inert gas to facilitate starting of the lamp. These lamps have been conventionally available since the 1940s.
Because of this construction, the utility of conventional fluorescent lamps is limited to environments where chances for breakage are relatively small. Also, thin glass lamps can be difficult and expensive to manufacture. In addition, because of their relatively high cost, conventional fluorescent lamps can be impractical for applications requiring numerous lamps.